The other night I had a dream where we were hitch-hiking somewhere on an open train of some sort (it had platforms with rails rather than actual carriages). Anyway we stopped for the night, and I "went to sleep" in our tent. In this dream-inside-a-dream I realized I was dreaming and did a nose RC which worked. Unfortunately it was all completely black and despite spinning when I felt it fading I "woke up" after about 15 seconds - losing lucidity.
So my hypothesis is based on the fact that normally when you fall asleep there's a fundamental change in your consciousness - plus the 90 minutes or whatever before REM starts - which causes you to forget you've just fallen asleep. But... When you "fall asleep" in a dream it's merely a shift in scene which takes less then a second - so that's why I was able to think "I'm asleep now! Must do an RC!" and gain lucidity.


Comments and/or questions will be appreciated.
PS: First (kinda dodgy) LD, wooo!